Transition Investigation on Stress-Strain Relationship of Sand-Silt Mixtures from Check Dam Deposit in Loess Plateau

Abstract

 To examine the influence of initial moisture content and confining pressure on the stress-strain characteristics of sand-silt mixtures (SSM), a series of consolidated drained triaxial shear tests were performed on reconstructed sand-silt mixtures with varying moisture contents (10%, 12%, 14%, and 16%). The results indicated that the stress-strain behavior of SSM is predominantly governed by the applied confining pressure, showing significant strain softening under low confining pressures and pronounced strain hardening under high confining pressures. Based on these experimental observations, a modified constitutive model, referred to as the Combined Plasticity Model (CPM), was developed by integrating elements of both the classical hardening model and the softening model. Moreover, a post-failure modulus was incorporated to describe the transition phenomena, and its transformation mechanism was thoroughly analyzed. Additionally, three illustrative case studies were provided to validate the analytical results and demonstrate their applicability through comparison with experimental data.